Effective and efficient solution for pin to pad contactor on wide range of smd package tolerances using a reverse funnel design anvil handler mechanism

Abstract

The problem of poor device pad to contactor pin presentation because of wide range of package size tolerance limited by process capability is minimized by a reverse funnel anvil design.

What is claimed is: 
     
         1 . A test system handler head comprising:
 a chuck, having a bottom end with rectangular sides;   an anvil formed in the bottom end of the chuck, wherein the anvil has a rectangular surface topology which includes a rectangular recess in the bottom end of the chuck;   wherein the sides of the rectangular recess are inside and spaced apart from the rectangular sides of the bottom of the chuck;   the rectangular recess having a top and a bottom, wherein the top of the recess is coplanar with the bottom of the chuck and the bottom of the recess is parallel and a distance “C” from the top of the recess, also wherein the sides of the recess are slanted away from the sides of the chuck;   the dimension of the rectangle “A” at the bottom of the recess is equal to the minimum tolerance size of the device to be contacted, the dimension of a rectangle “B” at the top of the recess is equal to the maximum size of the device to be contacted and the distance from the top the recess to the bottom of the recess dimension “C” is less than the maximum thickness of the device to be contacted but large enough to provided sufficient contact for alignment of the device with the chuck, thus allowing the device to protrude from the bottom of the chuck;   an alignment plate, wherein the alignment plate pre-aligns the device for presentation to the chuck; and   a vacuum pad for securing the device to the chuck during test.   
     
     
         2 . The test system handler head of  claim 1 , wherein the A, B and C dimensions for a nominal 3×3 mm device with a 1 mm thickness are A=2.90, B=3.10 and C=0.33 mm. 
     
     
         3 . A method of operating a test system chuck comprising:
 providing a chuck, with an recess formed in the bottom end of the chuck;   wherein the dimension of bottom of the recess is equal to the minimum tolerance size of the device to be contacted, the dimension the top of the recess is equal to the maximum size of the device to be contacted and the distance from the top the recess to the bottom of the recess is less than the maximum thickness of the device to be contacted but large enough to provided sufficient contact for alignment of the device with the chuck, thus allowing the device to protrude from the bottom of the chuck;   moving the a device to be tested closer to the chuck until they touch one another, wherein the recess in the chuck positions the device first correctly within its walls before vacuum pad initiates the action of picking it up, wherein Aligning the device with the chuck before vacuum pick-up, allows for better device alignment on the chuck as it ensures devices to be always at the center of the chuck regardless if it the device package dimension is at the minimum or maximum of the package tolerance; and   proceed to test the device.